Sustaining adherence to antiretroviral therapy (ART) is central to HIV management. For children in resource- limited settings, no well-validated measures of adherence exist. A reliable, valid measurement tool would provide more efficient, effective HIV care for this vulnerable population. My long-term goal is to work as a clinician-scientist who develops instruments to improve pediatric HIV care systems In resource-limited settings. In the near term, I want to focus on a reliable, valid, cost-effective way to measure children's ART adherence because this is central to the challenge of providing long-term HIV management. The objective of this application is to develop and test a reliable, valid instrument to measure pediatric ART adherence for children ages 0 to 14 years in western Kenya. The rationale for developing a validated adherence measure is to gain the ability to measure adherence accurately, test interventions to improve adherence, and assess if therapies optimize clinical outcomes. This work will be done within a long-standing US-Kenya partnership, the Academic Model for Providing Access to Healthcare (AMPATH). AMPATH cares for over 80,000 adult and pediatric HIV-infected patients in western Kenya, including over 2,800 children on ART. I plan to accomplish the research objective of this application by pursuing the following three specific aims: Aim 1: Develop a reliable, valid comprehensive pediatric ART adherence measurement questionnaire (CAMP - Comprehensive ART Measure for Pediatrics); Aim 2: Develop a reliable, valid, short-form version of the pediatric ART adherence measurement tool (SF-CAMP) for use as an adherence screening measure in busy clinical care environments; Aim S: Evaluate the field-readiness, implementation feasibility, and clinical utility of CAMP and SF-CAMP within the AMPATH HIV clinical care system in western Kenya. I also propose a course of training, study, and mentorship in the design and testing of health behavior measurement tools for International settings, the use of psychometric analyses to develop and validate clinical tools, and evaluation of pediatric HIV care. The combination of research work and my career development plan will enable me to become an independent clinician-scientist who can improve pediatric HIV care provision.